9927(  1) - 04/04/03 10:20  - [  1]

    PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS   ST ScI Use Only
                                                       ID:      9927
                                                       Version: 1
                                                       Check-in Date: 04-Apr-2003
                                                                      10:20:08

1.Proposal Title:
Measurements of core sizes in luminous early-type galaxies
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2. Proposal For  3. Cycle
AR               11
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4. Investigators
                                                                                     Contact?
    PI: Alister Graham                    University of Florida
   CoI: Dr. Peter Erwin                   Instituto de Astrofisica de Canarias          N

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5. Abstract

The sizes and slopes of "cores" in luminous elliptical galaxies have received
considerable attention since the HST first resolved these structures. It has been
suggested they are a signature of hierarchical formation models, due to the
gravitational ejection of stars by the coalesence of massive black holes following a
merger. To test such theories it is important to have accurate estimates of the core
properties. Almost all such measurements to date have used the popular Nuker model
to fit the surface brightness profiles within the central 10". However, we have
recently demonstrated that Nuker model analyses systematically overestimate core
sizes by factors of two or more, due to the intrinsic curvature of the profile
outside the core. We have developed a new model which explicitly allows for the
curvature in the outer light- profiles, and thus accurately recovers the core
properties as well. By using the complete WFPC2 mosaic, we can extract new light-
profiles from archived images of luminous, early-type galaxies which extend beyond
the arbitrary ~10 arcsecond radius used previously. This will enable us to derive
significantly more accurate core sizes and slopes, as well as global quantities such
as the Sersic index n, and in so doing better address the issue of core formation.
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                                                9927(  1) - 04/04/03 10:20  - [  2]

            Summary Form for Proposal  9927

  Item                         Used in this proposal
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  Proposal Category            AR
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